Control mechanism for preventing motor vehicles from creeping with provision for maintaining a constant restraining force



2,638,l 18 FROM y 1953 B. CHANDLER CONTROL MECHANISM FOR PREVENTING MOTOR VEHICLES CREEPING WITH PROVISION FOR MAINTAINING A CONSTANT RESTRAINING FORCE Filed Nov. 29 2 Patented May 12, 1953 CONTROL MECHANISM FOR PREVENTING MOTOR VEHICLES FROM CREEPING WITH PROVISION FOR MAINTAINING A CON- STANT RESTRAINING FORCE Irvin B. Chandler, Mankato, Minn., assignor to Minnesota. Automotive,

Inc., Minneapolis,

Minn., a corporation of Minnesota.

Application November 5, 1949, Serial No. 125,772

Claims.

This invention relates to a brake control mechanism to prevent creeping of a motor vehicle and is closely related to an application filed in the name of Simon W. Fraser and Irvin B. Chandler on January 3, 1949, Serial No. 68,886, entitled Control Mechanism for Cooperation with a Fluid Brake System to Prevent Creeping of a Motor Vehicle.

Although the mechanism disclosed in the above identified application operates very successfully. it has been found that variations in the current dueto variations in generator output, battery condition, and temperature of the solenoid coil produce a variance in the force exerted by the valve, and therefore in the pressure both maximum and minimum which is maintained in the fluid supply lines of the brake system.

- It is an object of my present invention to produce a mechanism for the same general purposes as the mechanism disclosed in the above identified application, but providing mechanism whereby variations in the current through the solenoid will not cause any variation in the pressure maintained in the fluid supply line.

Morerspecifically, it is an object to provide a ferrous metal plunger adapted to be actuated by an electrical conductive coil to project the same into a precisely predetermined position, said plunger carrying a valve element in sliding relation thereto and having a resilient element mounted in said plunger for urging said valve element outwardly against a fixed valve seat with a precisely predetermined pressure when said plunger is in projected position.

These andother objects and advantages of my invention will more fully appear from the following description made in connection with the accompanying drawings wherein like reference characters refer to similar parts throughout the several views and in which:

' Fig. 1 is a longitudinal vertical sectional view taken substantially through the center line of my improved mechanism, showing the plunger and valve in closed energized position;

. Fig. 2 is a similar view showing the plunger and valve in retracted de-energized position;

. Fig. 3 is a transverse vertical sectional view taken substantially along the line 3-3 of Fig. 2;

Fig. 4 is a transverse vertical sectional view taken substantially along the line 4-4 of Fig. 2, and;

L Fig. 5 is a diagrammatic view showing my control mechanism as connected in a conventional hydraulic brake system of a motor vehicle.

- As illustrated, in the accompanying drawings.

2 I provide a fluid control unit designated as an entirety by the letter A. This control unit has a casing member designated by the numeral 1 with an enlarged rear portion 8 of polygonal shape to receive a wrench thereon and forming an abutment shoulder to at the inner extremity thereof.

The sleeve 1 has a cylindrical inner chamber 9 extending therethrough and both the inlet pressure end Ilia and the outlet end lflb of said sleeve are internally threaded.

ened thereon. This enlarged portion provides a shoulder MD at the extremity of sleeve 1. adjacent end Hla. thereof. The core member II is hollow and has a partition I2 formed at the outlet end thereof and said partition has passage means formed therethrough such as a plurality of flow passages 13 formed around the outer portion thereof and a central seated flow passage [4 formed in the center thereof. A valve seat I 5 surrounds the inlet end of flow passage I4 and projects rearwardly into chamber 9 therefrom.

An annular check valve I6 is mounted in sealed relation against the outlet side of partition .IZ-to permit flow of fluid through the passages l3 in only one direction and positively prevent backflow therethrough. A spring I! and annular reinforcing ring IB are provided to resiliently hold said valve l6 against the outlet side of partition Hc therein in addition to holding the spring I! in position within said core member He.

low substantially unrestricted flow of fluid from chamber 9 into chamber llc through passages I3..

A ferrous metal valve carrying plunger or body 20 is inserted in valve chamber 9 in sliding relation therein. The body 20 has a valve receiving recess formed longitudinally through the forward and central portion thereof and a valve 2 I is S1Id-. ably mounted therein. A spring 22 of accurately predetermined tension is mounted behind the valve member 2| to normally urgethe same out-,

wardly toward valve seat 15. A sealing element Zla is formed in the outer end portion of valve 2| to be sealingly seated against seat 15 when the body 20 is in forwardly projected position, as shown in Fig. l. A stopelement such as the annular ring 23 is formed at the forward end of body 20 to positively engage partition l2 and position said body 20 in a precisely predetermined projected position. This permits a pre Plug member I9 is threadably inserted in the outlet end of core II and forms a chamber The spring, of course, is of very light tension to a1 cisely predetermined increment of compression to be produced in spring 22 when the body 25} is in forwardly projected position, and thereby exert a predetermined pressure on the valve 23 against seat 15. The body 20 has a number of by-pass flow passages formed therein, such as the longitudinal passage 26a, transverse passages 20b, and longitudinally formed groove passages 200 to permit unrestricted flow of fluid through chamber 9.

An annular coil of electric conductor wire 25 is concentrically mounted around the outer portion of sleeve 1 and a pair of annular end plates 24a, and 24b are respectively fixed at the ends thereof to respectively abut the shoulders lab and 8a. A sealing washer 25 is interposed between the shoulder Nb and the end of sleeve 7 adjacent thereto. The control mechanism disclosed in the foregoing description is connected on a conventional motor vehicle in the same manner as that described in my above identified co-pending application. In the form shown, the control is connected into the fluid supply line to the brake actuators of the rear wheel brakes with the plug l9 disposed toward said brake actuators. The three switches 2t, 27 and it are respective- 1y interposed into the solenoid circuit to control energization thereof. The switch 2'6 represents an ignition switch. Switch 21 is a switch actuated by the accelerator pedal 2t, and is closed when the accelerator pedal is released. Switch 28 represents a manually operated master control switch which can be opened or closed under the control of the operator. 3G represents a conventional brake pedal, and Si is a conventional master cylinder. As was described in my above identified coepending application, both the ignition switch 26 and the master switch 28 must be closed, and whenever the accelerator pedal is completely released the solenoid coil 12 i will be energized. The energization of the coil 24 produces a magnetic field and magnetizes the core member H, which attracts the ferrous metal valve carrying body 2i; to project said body forwardly and firmly engaged the abutment member 23 against the face of partition l2 on the inlet side thereof to precisely position said body relative to said partition and produce a predetermined increment of compression in spring 22. With the body 26 in projected position and the valve 2i seated against seat i fluid is still permitted to flow to the brake actuators through passages 26a, Zilb and Elle, and outwardly from chamber 9 through passages 53 and into the fluid supply lines. When the brake pedal to is released and the fluid seeks to return, the check valve [6 seats itself to close off passages l3 and the only open passage permitting back flow of fluid is the central seated passage i i. The valve 2| and the pressure exerted thereby against said valve seat 15 by the compression of spring 22 directly opposes the back flow of fluid through seated passage l4 and thereby maintains a precisely predetermined residual pressure in the fiuid supply line and holds the brakes in applied position with a predetermined force regardless of the magnetic thrust exerted by the coil 2t in excess of a predetermined minimum required force. Immediately upon de-energization of the coil 24', as by stepping on the accelerator pedal 29, the body 26 is permitted to shift rearwardly intov retracted position, as shown in Fig. 2, and releases the compression from spring 22 and the pressure in the brake line. The increment of shifting movement of the body is sufficient to 4 permit the valve 2| to be shifted away from the seat l5 by the back-flow fluid pressure and permit complete expansion of the spring 22 and ermit unrestricted flow of fluid back to the master cylinder.

It will be seen that my mechanism maintains a precisely predetermined pressure within the fluid supply line whenever the solenoid is energized at the time the brakes are applied. The

\ solenoid is designed so that the amount of thrust thereon is always suihcient to project the plunger 28 firmly against the partition l2 regardless of minor variations in generator output, battery condition, and temperature of coil 24. In other words, my improved mechanism eliminates any. maximum limit on the solenoid thrust since it is not the thrust of the solenoid that determines the force exerted upon the valve 2|, but rather the thrust exerted by a predetermined increment of compression of the spring 22. The relation of the diameter of the passage M to the diameter of the hydraulic plungers in the brake actuators along with the force exerted by spring '22 determines the amount of force exerted on the brake actuators and can, of course, be varied to any desired degree by the manufacturer. Whenever the force exerted by the pressure on the fluid in the line exceeds the force exerted by the spring 22 fluid will be permitted to bleed back through seated passage Hi and return toward the master cylinder. By positioning the body 28 in a precise projected position the increment of compression in spring 22, and thus the force exerted thereby, will always be the same.

It will, of course, be understood that various changes may be made in the form, details, arrangements and proportions of the parts without departing from the scope of my invention.

What I claim is:

1. A fluid control valve for use with hy raulic brake systems and comprising a hollow cas ing member defining a valve chamber with a flu-e id inlet at the pressure end thereof and a fluid outlet at the other end thereof, a partition interposed across an intermediate portion of said chamber and having flow passage means formed therethrough, check valve means sealingv off a portion of said passage means on the outlet side of said partition to prevent backflow of fluid therethrough, valve seat means surrounding the inlet side of the other passage means, a valve carrying body shiftably mounted in said, chamber on the inlet, side of said partition and constructed to permit unrestricted bypass flowof fluid in both directions, a valve Shiitably mounted at thev end of said body adjacent Said partition and positioned to en age, when said body is. shifted toward the inlet side of saidpartition said valve seat means surrounding the inlet side of said seated passage means and directly opposing the backflow of fluid therethrough, resiiiently yieldable means. permittin shifting movement of said valve relative to the body and urging said valve against said seat means with a predetermined force when said body is shifted toward saidpartition into pro jected predetermined relation thereto, and means for instantly projecting said body 110,-- ward said partition.

2. A fluid control valve for use with hydraulic brake systems and comprising a hollow casing member defining a valve chamber with a fluid inlet at the pressure end thereof and a fluid. outlet at the other end thereof, a ferrous. metal partition interposed across an intermediate portion of said chamber and having flow passage means formed therethrough, check valve means sealing off a portion of said passage means on the outlet side of said partition to prevent back-- flow of fluid therethrough, valve seat means surrounding the inlet side of the other passage means, a ferrous metal valve-carrying body shiftably mounted in said chamber on the inlet side of said partition and constructed to permit unrestricted by-pass flow of fluid in both directions, a valve shiitably mounted at the end of said body adjacent said partition and positioned to engage when said body is shifted toward the inlet side of said partition said valve seat means surrounding the inlet side of said seated passage means and directly opposing the back-flow of fluid therethrough, resiliently yieldable means permitting shifting movement of a valve relative to the body and urging said valve against said seat means with a predetermined force when said body is shifted toward said partition into predetermined projected relation thereto, and an electro-magnetic coil surrounding said i'errous metal partition and instantly shifting said ferrous metal body into projected predetermined relation to said partition when said coil is energized.

3. A fluid control valve for use with hydraulic brake systems and comprising a hollow casing member defining a valve chamber with a fluid inlet at the pressure end thereof and a fluid outlet at the other end. thereof, a partition interposed across an intermediate portion of said chamber and having flow passage means formed therethrough, check valve means sealing off a portion of said passage means on the outlet side of said partition to prevent back flow of fluid therethrough, valve seat means surrounding the inlet side of the other passage means, a valvecarrying body shiftably mounted in said chamher on the inlet side of said partition and constructed to permit unrestricted by-pass flow of fluid in both directions, the end of said body adjacent said partition having a recess extending longitudinally rearwardly a substantial distance therein, a shiitable valve element mounted in said recess for longitudinal shifting movement relative to said body and having seat-engaging and sealing means at the partition end thereof constructed to engage when said body is shifted toward the inlet side of said partition said valve seat means surrounding the inlet side of said seated passage means and directly opposing the back-flow of fluid therethrough, resiliently yieldably means associated with said shiftable element for urging the same against said seat means with a predetermined force when said body is shifted into projected predetermined relation to said partition, and means for instantly shifting said body into projected predetermined relation to said partition.

4. A fluid control valve for use with hydraulic brake systems and comprising a hollow casing member defining a valve chamber with a fluid inlet at the pressure end thereof and a fluid outlet at the other end thereof, a partition interposed across an intermediate portion of said chamber and having flow passage means formed therethrough, check valve means sealing oif a portion of said passage means on the outlet side of said partition to prevent back-flow of fluid thercthrough, valve seat means surrounding the inlet side of the other passage means, a valvecarrying body shiftably mounted in said chamber on the inlet side of said partition and constructed to permit unrestricted by-pass flow of fluid in both directions, the end of said body adjacent said partition having a recess extending longitudinally rearwardly a substantial distance therein, a shiltable valve element mounted in said recess for longitudinal shifting movement relative to said body and having seat-engaging and sealing means at the partition end thereof constructed to engage when said body is shifted toward the inlet side of said partition said valve seat means surrounding the inlet side of said seated passage means and directly opposing the back-flow of fluid therethrough, a resiliently compressible member interposed between the rear end of said recess and said valve element for resiliently urging said valve element forwardly toward said partition, means for instantly shifting said body into projected predetermined relation to said partition, and positive stop means interposed between said partition and the adjacent end of said body to maintain a precisely pr determined projected position of said body relative to said partition whereby a precisely predetermined increment of compression is produced in said compressible member to resist with a predetermined force back-flow of fluid through said seated passage means when said body is in projected position.

5. A fluid control valve for use with hydraulic brake systems and comprising a hollow casing member defining a valve chamber with a fluid inlet at the pressure end thereof and a fluid outlet at the other end thereof, a partition interposed across an intermediate portion of said chamber and having flow passage means formed therethrough, check valve means sealing off a portion of said passage means on the outlet side of said partition to prevent back flow of fluid therethrough, annular valve seat means surrounding the inlet side of the other passage means and protruding rearwardly from said partition toward said fluid inlet and providing a fiat sealing surface, a valve-carrying body shiitably mounted in said chamber on the inlet side of said partition and constructed to permit unrestricted bypass flow of fluid in both directions, a valve shiftably mounted at the end of said body adjacent said partition and having a resilient slightly compressible sealing element mounted thereon and positioned to engage when said body is shifted toward the inlet side of said partition. the flat sealing surface of said annular protruding valve seat means and, directly opposin the back-flow of fluid through said seated passage means, resiliently yieldable means permitting shifting movement of said valve relative to the body and urging said valve sealing element against the flat sealing surface of said annular protruding seat means with a predetermined force when said body is shifted toward said partition into projected predetermined relation thereto, and means for instantly projecting said body toward said partition.

IRVIN B. CHANDLER.

References Cited in the file of this patent UNITED STATES PATENTS Number 

